Process of smelting iron ores.



PATENTED DEC. 25, 1906.

I G. ELLIS. y.

rRoCBss 0F SMBLTING IRON DRES.

APPLIQATION YILED DBO. Z6. 1905.

UNITED sT-Arns- PATENT OFFICE..

No. 839,126. y

To all whom it. may concern.- l Be it known thatf I, CARLETON ELLIS, acitizenof the United States, and, a resident of WhiteIlains, in thecounty of New York and State of New York, have invented certain new anduseful Processes of-,Smelting Iron Ore, of which the followin'gis aspecifica- This invention relates to a process of reducing iron ore in afinely-divided condition or in a form which renders its smelting in thelblastfurnace a troublesome operation unless briquetmg'is're'sorted to;and the object of this invention is to economically reduce fine ores,such as ma netic concentrates andthe like, to a. metalic state and underconditions which permit a greater economy of fuel than vthat secured inblastefurnaces and, moreover, without the usual limitations with respectto the fuel employed. t l' Theyblast-furnace is'not a self-contained aparatus.. Expensive units are required,` inc uding stoves,blowing-engines, &c., to secure a satisfactory output of metal -withreasonable economy of operation. Unfortunately the blast-furnace is a-sort of gas-producer. It is impossible'to conduct its operation; insucha manner that complete combustion is secured. l'Hence the arrayofaccessories reqisitein a modern blast-furnace lant. P M inventionprovides for .the complete com u'stfion of the fuel employed and fortheemployment of ineXpen'sIve units. More-Y over, the smelting apparatusis self-contained, anditherein as la "heating agent may be used avariety of cheap fuels in place'of the eX- ensive hard "coke which isrequiredin the blast furnace to bear the burden of the charge without"crumbling. The blast-furnace islimted in height, and'hence the sensivble heat lost in the form of esca ing gases is considerable, and owingtothe imitation of height the `sensible heat losses cannot be reducedbelow a certain uneconomical'point.`

My invention rovides for cooling ofthe products of com ustionto a verylow temerature, so that the sensible heat loss is re` uced to avminimum,and economy'in fuel, as compared with the blastfurnace, results.

,Eiorts have been made to vreduce iron ore without" the agency of theblast-,furnace but such methods have not been entirely successful, sofar as I am advised, owing, among other reasons, tothe small outputobtainable. Some proposals have been made'for the pro` Specification ofLetters Patent. l Application filed December 26,1995. Serial No.293.178.

vrafaelitas Dec. 25, 19oe.

duction of spongy iron; but it has been f ound that the reduction ofiron ore to spongy iron as ordinarily conducted is avery slow process.

My invention permits of the production .of either spongy iron or molteniron and steel, according to the particular method of operation adopted.

The ore which `I refer to treat by my process is a puregrade ofmagnetite. Magnetic concentrates containing about sixty- 4six per cent.of iron or over andfrom one to three per cent. of silica are s uitable,althouv h I prefer a pure magnetite when such is o tamable, for inWorkin with an ore of this sort there is very little s ag to deal with,and,

`in fact, only that small lquantity` of sla is required which sufficest'o protectI the mo ten metal.

The direct reduction of iron ore by 'means other than the blast-furnaceembrace the following features-of operation. There should be freemovement ofthe-ore in the receptacle employed. The products ofcombustion should leave the'furnace substantially burned outthat is,containing -no combustible mat.- ter which calls for stoves, boilers,gas-engines, &c., for utilization. The waste gases should also de art ata low temperaturein order to minimize heat losses from this source.v Themetal should preferably berremoved inthe liquidcondition, as s ongy ironoxidizes very readily if transportecfwhile hot. Means should be providedfor the efficient separation of the 'sla The operation should becontinuous and'c ing alarg'e output. yThe linings of the fur'- naceemployed must not be attacked by the orey or ux at the temperaturesemployed.

' The furnace should be so constructed that no1 clogging and building upofthe ore to form obstructing masses is likely tooccur. Means must-also'be provided for` theintroduction of "fluxes and carburizing agents, thelatter being' preferably introduced when the ore'hfas been heated nearlyto the reduction temperature in order thatcarbon may be absorbed by theore before it has opportunity to lgasify. i

In order to Withdraw the metal from t e furfirst forms.

the metal to a pfoint at which it `easily fuses and may' be Withdrawn inthe melten State, thereby permitting a separation of the metal from theslag. i rlhe reduction of the ore calls for a. reducing atmosphere andat the same time for a large output a temperature.

It is not dfeult t0. Teduee the magnetic OXd to the lowest o xd ofiron-namely, FeG-but it is difficult to carry the ore past its lowestdescribed..

state 'of oxidation to the metallici state. Hence it is necessary tolprovide a powerful reducing atmosphere. A fiame of hightempereture.elfdiueily is oxidizing, es en eXeeSS of 'air must b eadmitted te securethe rapid combustion resulting in the development of hightemperakture.-v 'Itis therefore necessary to, control the flame orsupply the heat in such a manner that rapid reduction is possible Allthese features above described are embodied in the process to behereinafter My process of manufacturing iron or steel consists in thetreatment of partially-heated ore under powerful reducing conditionswith e, hightemp-eretre 11eme Q1 heating agent and in bringing the gasesof combustion resulting from such treatment into intimate I contact withthe ycold ore, thereby causin the heat occurs. u Iplished in a rotaryinclined kiln. In order to secure the reducing atmosphere, Imay use vtwo flamesof different characters, the one I travel of the' o're.

having ins carrying an abundance of air, and therefore havingatemperature, and the other V cient air or no air at all. For theattainment efy reelileills.Conditions the latter Haine or enfrenta-nitybe interposed between the high-temperature flame and the' ore in themanner described in'Patent No. 863,886. Another method of securing theVreducin conditions is to enter carbonaceous materia at Some point inthe path of the Prior investigators have attempted to feed ore and'coalor coke into theupper 'end of an inclinedrotary kiln and y e 'Singlehigh-temperature flame in the {Wifefl' 'pa/rtf.,-v it being vsupposedthat the fi'e'l introduced withl the ore would be sufficient to performreduction. Actually it was found that lthe carbon burned away before itreached the lower par`t\ of the kiln and very little of the ore wasreduced to the metallic state, although a large portion of it wasreduced tol ferrous oxid. 7 Furthermore, as

combustion of this fuelr occurred in the' upper vpartv ofthe kilnthe'products of combustion j depart-edel', a high temperature and theheat loss'from thisl source'was considerable.

process involves the introduction of the carbonaceousfuel ata point nearthe final zone 'A the charge downwar of reduction, and thereforeobviatcs the above-mentioned difficulties.

4 For the performance of the process here set forth and claimed I havedevised a certain lnovel combination of apparatus whereby the forces andmaterials concerned in the process are caused to coperate in therelation necessary to its exercise, which apparatus is also claimedherein.

In the` accompanying diagrammatic drawing 4the longitudinal section of areducingchamber is depicted and connecting thereto is'shown elevation arotary kiln constructed to reheat the ore.

n the drawing, 1 is a rota inclined kiln lined with refractory materiaand rotating on the bearin s 2,.

' 3 is the'drlvingmechanism, The upper part of the kiln is inclosed bythe housing 4, on which is situated the stack 5. The hopper 6 containsthe cold ore which is fed by the conveyer-7 into the chute 8, from whichit discharges into the upper end of the kiln.

9l is the reducing-chamber pro er, 'rovided with the stationary inclinedeart 1 10 and the metal-collecting pit. 11, having the tapping-holes 12and 13 for the slag and metal, respectively.

` 14 and 1.5` are pipes or ports through which V the fuel and air areadmitted. reheating the fresh ore' I prefer 14 is a special fuel-pipefor use when a very high temperature 1sV required iny the upper part ofthe inclined hearth. The port 14 ordinarily iscconstru'cted to deliver amixture of air and fuel in such proportions that a high-temperaturefiame is produced, while the port 15.i,s arranged to produceareducingflame.

At 16. are shown doors in the side walls of the furnace through whichbars may be introduced for assistin in the movement of dly along theinclined hearth.

At 17 is situated a conveyer or feeding apparatus by means of whichcoal, coke, or

other carbonaceous fuel cr carburizing agent may be introduced into thereducing-chamber, preferably underneath the charge of ore, in such amanner as to be-readily mixed therewith'. i l

In operating this apparatus by my process I feed the ore in apredetermined amount from theliopper 6 into the kiln 1, which is put inrotation and thereby a itates and mixes the ore in a' thoroug manner.Through the ort 14 I introduce a blast of owdered coa and air or a jetof oil or other el, it being understood that the air ma be admitted inadmixture with the fuel or, i desired, in proximity to the fuel throughadjacent ports not here specifically shown, but whose constructionandarrangement will be alplparent toy those skilled in the art to which t sinvention pertains. Ordinarily I prefer `to have sufficient air admittedfor the com- IOO IIO

loil or a current of producer or water'gas or similar fuel may beentered, thus interposing between the high-temperature ame produced bythe combustion of the fuel entering strongly reducing atmosphere, whichmakes rapid reduction possible: The feeding apparatus 17 deliversfinely-divided coal or coke onto the'hearth and the ore falling from thelower end of the kiln 1 and ina partially; heated condition mixes moreor less with the carbonaceous fuel enterin by the feed 17, and thismixture moves ownwardly along thehearth 10. By the combustion of thevfuel admitted through 17 the reducing'atmosphere is augmented and atthe same time sufficient carbon is introducedtoper'mit of carburizingthe metal to an extent suffiwith the ore may be thorough. lUnder cer-,ameof an oxidizi cient to permit of the withdrawal Vofthe latter in amoltencondition. As a flux calcareous or silicious -matter according tothe nature of the ore may. b e introduced either with the ore from thehopper 6 or through the conveyer 17. It is preferable, however, tointroduce the ii material at the upper end of the'kiln in order that the4admixture tain conditions it isy possible to' have onlyT a nature inthe chamberl 9 and to dispense with the reducing-current otherwisevadmitted throu h` the port 15. Thismay be accomplished y introducing afsomewhat` .larger amount of carbonaceous fuel (c. gQ, coke) than wouldotherwise be used through the conveyer 17 The reduction of this carbonwill create the necessary reducing atmosphere, and, too, Without thatpremature combustion consequent on the introduction-v of carbonaceousmaterial at the stack end ofthe apparatusly It is evident that thestationary. hearth 10 lor chamber 9 may be of a rotary type, the

carburizing agent being admitted at its upper endin manner abovedescribed. I A ro`- tary kiln, however, for a reducing-chamber for'production of the molten'metal is not wholly suitable, owing to thehigh temperature employed and consequent trouble from the linings, whichin rotary furnaces, owing to the jarrin &c., 4of the apparatus, causes-their rapid vestruction. For thelmanufacture of spon iron where thetemperatures 4are not as high the rotary kiln may beadvantageouslyemployed. If the sponge `is to be used in an open-hearth furnace as anaddition td molten pig, reduction Vof the ore on the hearth 10completely to the metallic state is unnecessa Thel apparatus herewithshown is `also adapted for maki spongy iron, although the output is smer thanv when the conditions aremade such-that the equilibriumv moltenmetal is produced. I The rotary kiln 1 may be of any length desired. Alength'of from eighty to one hundred feet is suflicient to reduce thestack-gases to a low temperature.

' With ores which have a ytendency to agglomerate when subjected to-ahigh temperature and which therefore give trouble through failure tomove properly along the hearth 10 it is possible t o provide the hearthwith a shaking or tiltin motion, whereby the feeding is rendered uniorm. Such ores may, however, be reduced to sponge only and subsequentlyballed by'mampulating with a bar through the openings 16. The balls soproduced may then be squeezed and rolled, &c.

It should be borne in mind that under certain conditions carbon monoxidis in itself an oxidizing agent'. Carbon Imonoxid deposits carbon by thereaction 2CO:C-{-CO2 but its deposition occurs, so far as I know, onlyin the presence of free iron or metals of the iron group and is not.brought about by the oxids Vof these metals. Apparently carbon monoxiddoes not oxidize metallic iron directly, but indirectly, in that theiron causes deposition of carbon and formation of carbon dioxid, whichlatter then oxidizes iron -to ferrous oxid, regenerating carbon monoxid.This reaction proceeds until e ui- .librium between the various reactingbo ies is attained--that is to say, between metallic iron, ferrouso'xid, carbon, carbon monoxid,

and carbon' dioxid. Equilibrium can only,

occur, according to the phase rule, for a sin- -gle partial pressure ofeach of the two gases and `a single total pressure of both gases. If thepartial pressure of carbon monoxid and carbon dioxidv inA the furnacetaken together are greaterthan this single critical pressure, thenoxidation of the iron can take placeiwithv deposition of carbon. If thepressure is less, fcarbon can be deposited, but no iron oxidized. y Thevalue of this critical equilibrium pressure varies only with themillimeters; at 700 centigrade the' critical equilibrium pressure isthree hundred and five millimeters; at 750 centigrade the criticalpressure is five hundred and thirty-five millimeters; at 800, centigradethe critical equilibrium pressure is eight hundred millimeters.

Since the partial pressure noxid and carbon dioxid are seldom less thantwo hundred and fifty millimeters, a reduction can take place down to690 centigrade,

of carbon moters; at 650 centigrade the critical equilibrium pressure is.one hundred and forty-five l `and below that it stops.` Thereforecondimost eflicient operation to conform closely to the'aboverequirements.

Having now described my invention,l what I claim, and desire to secureby Letters Patent, lS-- i f I,

1. The process. of reducing iron ore which consists in the preliminarystep of drying and .heating the ore withawaste gasesof combustion and inthe secondary. step of exposing the ore in a thin layer to areducing-flame. I

- 2. The processof reducing iron ore which consists in -the preliminarystep of drying and -heating the o re while agitating in contact with hotwastegases of combustion and inl the secondary step of exposing a layer.of the ore to a reducing-flame.

3. The process. of reducmg iron ore Awh1ch consists 1n exposing aprogressively-advancingstream of magnetic iron ore toy a current of hotproducts of combustion; in mixing with the heated ore a predeterminedquantity of a lluxing and va carburizing agent;in subjecting the mixturetothe simultaneous action of a high-'temperature flame and an.interposed .reducing atmosphere, thereby heating said mixture to a hightem erature, and in `collecting and separating t 'e metal and slag. 4.The process of manufacturing iron or steel. which comprises the exposureofthe partially-heated ore under reducing conditions to ahightemperature flame burning in free space; and in bringing the Wastegases from said flame into contact with the .cold ore thereby causingthe latter to becomepartially heated.

5. The process 0f manufacturing iron and steel which comprisesV -thetreatment of the artially-heated ore in admixture with ,carbonaceousmaterial with a high-temperature flame y and in bringing the waste gasesfrom said flame into contact with the cold ore, thereby causing thelatter to become partially heated; and in agitating the ore during suchpartial-. heatin'g, ythereby causing it to acquire a uniformtemperature. 6.. The process of manufacturing iron and steel whichcomprises the treatmentof a partially-heated and yprogressively-advancing mass of iron oi'eunder kreducing `conditionswith flame of high temperature; and in bringing the waste gases fromsaid flame into contact With a stream of fresh ore, thereby causing thelatter to become partially heated.

7. The process of manufacturing iron which com rises the treatment of apartiallyheated and)progressively-advancing mass of iron ore underreducingconditions with a flame of high temperature; in removing themetal and slag in a molten state; in separating the former from thelatter by gravity; and in bringing the waste gases from said flame intocontact with a fresh supply of ore therebycausing the latter to becomepartially heated; and in agitating the fresh ore during such preliminaryheating.

8. The process of manufacturing iron which consists in the treatment ofa progressively-advancing stream of partiallyheatedmagnetic concentratesunder reducing conditions with a high-temperature flame; in adniixingtherewith at the beginning of such treatment a quantity of carbonaceousmaterial; and in subjecting said .stream to a `temperature sufficient tomelt 'the metal; in separating the slag from the metal; in bringing thewaste gases from said flame into contact with the cold ore therebycausing the latter to become partially heated, and in agitating said oreduring such partial heating.

9. The rocess of manufacturing iron WhichV cons1sts in treating atraveling layer of iron ore with the waste gases from a hightemperatureflame burning in free space, advancing such layer into contact with saidflame, during contact admixing powdered fuel with the advancing ore, andremoving the thereby-produced iron from the action of the flame.

10. The process of manufacturing `iron Which consists in treatingatraveling layer of iron ore with the waste gases from a hightemperatureflame burning in free space, advancing such layer into contact with saidflame, during contact admixing powdered fuel with the advancing ore, andremoving the thereby-produced iron from the action of the flame bytransmitting into and through a reducing atmosphere.

Signed at New York, in the county of New York 'and State of New York,this 23d day of December, A. D.V 1905. y

- CARLETON ELLIS. Witnesses:

FLETCHER P. ScoFrELD,

FRED. I. SMITH. l

